The present invention concerns a wind power installation comprising a pylon and a rotor arranged on the pylon and having at least one individually adjustable rotor blade, comprising a device for detecting the wind direction and a device for detecting the azimuthal position.
Such wind power installations generally have an active drive for tracking the wind direction. The drive rotates the machine housing of the wind power installation in such a way that the rotor blades of the rotor are oriented in the direction of the wind if the installation is in the form of a windward-type rotor member. That drive which is required for wind direction tracking is usually an azimuthal drive which is usually disposed with the associated azimuthal bearings between the top of the pylon and the machine housing.
In the procedure involving the machine housing tracking the wind direction, an operational wind measuring system supplies a mean value in respect of the wind direction over a certain period of time, for example ten seconds. That mean value is always compared to the instantaneous azimuthal position of the machine housing. As soon as a deviation exceeds a given value, the machine housing is correspondingly adjusted to track the change in wind direction so that the deviation of the rotor in respect of the wind direction, being the yaw angle, is as slight as possible in order to avoid power losses.
The way in which a wind direction tracking procedure is implemented in known wind power installations is described in “Winkraftanlagen”, Erich Hau, 2nd edition, 1996, pages 268 ff. and 316 ff., respectively.
In addition such a wind direction tracking procedure is known from laid-open application DE 199 20 504.
A disadvantage with those known arrangements however is that the azimuthal drives which are frequently in the form of electric motors have to be actuated for each wind direction tracking operation. Frequent actuation results in a high loading and correspondingly relatively rapid ageing and a high level of wear in such drives.
Furthermore a disadvantage with known structures of that kind is that increasing sizes of installation logically require more or larger drives in order to be able to implement the required adjusting movement. However, particularly in the case of a fault or if replacement is necessary, those larger drives require a considerably higher level of expenditure as they can only be moved out of or into the machine housing by means of a crane. If a hub height of 130 m and more is further factored into the considerations, installations which are set up on land already involve a considerable level of expenditure; however that rises far beyond all acceptable limits if the installation is an offshore installation. It will be appreciated that the amount of space required for such drives also increases.